iStock(NEW YORK) -- A man suspected of murdering 17-year-old Bianca Devins alerted police to the killing by posting photographs of her dead body on multiple social media platforms, police said.

Now, Instagram is facing criticism from social media users for allegedly failing to swiftly remove the gruesome images.

"I have seen the pictures. I will FOREVER have those images in my mind when I think of her," Devins' stepmother, Kaleigh Rimmer, wrote on Facebook on Monday morning. "When I close my eyes, those images haunt me."

Instagram users took matters into their own hands by posting photos of pink clouds in Devins' honor to drown out the images of her untimely death, technology and business magazine Fast Company reported.

Police in Utica, New York, say that 21-year-old Brandon Clark -- who Devins met on Instagram two months ago -- killed her with a knife in the early hours on Sunday, and then posted photos of Devins' corpse onto Instagram, Snapchat and gaming site Discord.

Clark has been charged with second-degree murder, police said.

The Utica Police Department confirmed the authenticity of the images in a press release.

When social media users reported the images, Instagram, which is owned by Facebook, sent a reply saying that the images had been reviewed, and they did not violate its community guidelines.

A spokesperson for Facebook told ABC News that the photos were later removed from the platform. But the company did not immediately say how long the images had been allowed to stay up, or why users had been told the images were in keeping with its content policies.

"Our thoughts go out to those affected by this tragic event. We are taking every measure to remove this content from our platforms," the Facebook spokesperson said.

A spokesperson for Discord said in a statement to ABC News: "We are shocked and deeply saddened by this terrible situation. We are working closely with law enforcement to provide any assistance we can. In the meantime, our hearts go out to Bianca’s family and loved ones."

A representative for Snapchat did not immediately respond to ABC News' request for comment.

Clark's accounts on both Instagram and Facebook were removed after police identified him on Monday, and the hashtags #yesjuliet, #yesjulietpicture, #checkyesjuliet and #yesjulietvideo, which may coincide with Clark's Instagram handle, @yesjuliet, have been blocked to stop the spread of the images, according to Facebook. The platform is also using technology that allows them to proactively find other attempts to upload the image and automatically remove them before anyone sees them, Facebook said.

The platform says they are currently in touch with law enforcement.

Devins graduated from high school in June and planned to attend the Mohawk Valley Community College in the fall. The pair had become acquainted with each other's families, but a mutual friend described their relationship to Rolling Stone as strictly platonic.

On Saturday, Devins and Clark went to a concert in New York City and headed back to Utica around 10 p.m., police said. Investigators believe the two had an argument, which led to Clark allegedly killing Devins with a large knife in the early hours on Sunday.

Police learned of Devins' murder after receiving several 911 calls Sunday morning detailing that a man had posted to multiple social media platforms, and stated he killed his girlfriend and was threatening to harm himself, according to a press release from the Utica Police Department.

Clark also called 911 and made "incriminating statements with respect to the homicide" and suggested he planned to harm himself, police said. As an officer approached, he began to stab himself in the neck with a knife, police said.

After Clark called police, investigators tracked his location and found him lying on the ground in a wooded area next to a black SUV. Police then noticed what appeared to be a body lying beneath a tarp and, when asked about Devins' whereabouts, police said Clark pulled out his phone and attempted to take a selfie of himself next to Devins's body.

As an officer approached, he began to stab himself in the neck with a knife, according to authorities.

Clark was taken into custody and brought to the hospital, where he underwent emergency surgery for "severe injuries," police said. He is still recovering from his injuries at the hospital and has not yet been booked into jail.

In a statement issued by police, Devins' family described her as a talented artist and "wonderful young girl."

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